506725-01
Page 31 of 48
Issue 1109
Electrical
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
Electrostatic discharge can affect electronic
components. Take precautions during furnace
installation and service to protect the furnace’s electronic
controls. Precautions will help to avoid control exposure
to electrostatic discharge by putting the furnace, the
control and the technician at the same electrostatic
potential. Neutralize electrostatic charge by touching
hand and all tools on an unpainted unit surface, such as
the gas valve or blower deck, before performing any
service procedure.
CAUTION
The unit is equipped with a field makeup box on the left
hand side of the cabinet. A field-provided make-up box can
be installed on the exterior of the right side of the furnace to
facilitate installation. Seal unused openings on left side with
plugs removed from right side. Secure the excess wire to
the existing harness to protect it from damage.
Refer to Figure 47 for field wiring and Figure 48 for schematic
wiring diagram and troubleshooting.
The power supply wiring must meet Class I restrictions.
Protected by either a fuse or circuit breaker, select circuit
protection and wire size according to unit nameplate.
NOTE:
Unit nameplate states maximum current draw.
Maximum Over-Current Protection allowed is 15 AMP.
Holes are on both sides of the furnace cabinet to facilitate
wiring.
Install a separate (properly sized) disconnect switch near
the furnace so that power can be turned off for servicing.
Before connecting the thermostat check to make sure the
wires will be long enough for servicing at a later date. Make
sure that thermostat wire is long enough to facilitate future
removal of blower for service.
Complete the wiring connections to the equipment. Use the
provided unit wiring diagram and the field wiring diagram
shown in Figure 47. Use 18 gauge wire or larger that is
suitable for Class II rating for thermostat connections.
Electrically ground the unit according to local codes or, in
the absence of local codes, according to the current National
Electric Code (ANSI/HFPA No. 70) for the USA and current
Canadian Electric Code Part 1 (CSA standard C22.1) for
Canada. A green ground wire is provided in the field makeup
box.
NOTE:
The gas furnace contains electronic components
that are polarity sensitive. Make sure that the furnace is
wired correctly and is properly grounded.
FIGURE 44
MAKE−UP
BOX INSIDE
CABINET
Left side
INTERIOR MAKE−UP BOX
(FACTORY− INSTALLED LEFT SIDE)
FIGURE 45
MAKE−UP
BOX
OUTSIDE
CABINET
Right Side
EXTERIOR MAKE−UP BOX
(FIELD PROVIDED RIGHT SIDE)
Accessory Terminals
One line voltage “EAC” 1/4” spade terminal is provided on
the furnace control board. Any accessory rated up to one
amp can be connected to this terminal with the neutral leg
of the circuit being connected to one of the provided neutral
terminals. If an accessory rated at greater than one amp is
connected to this terminal, it is necessary to use an external
relay. See Figure 49 for control board configuration. This
terminal is energized when the indoor blower is operating.
